Worldwide, water reuse is promoted as an alternative for water scarcity, however, wastewater effluents have been reported as possible contaminants to surface water. The failure of some wastewater treatment processes to completely remove organic matter and some pathogenic microorganisms allows them to initiate infections. This manifests more in communities where surface water is used directly for drinking. To assess water quality, bacteria alone cannot be used as it may be absent in virus-contaminated water. This study was carried out to assess the quality of two wastewater treatment plant effluents from the Eastern Cape Province of South Africa. Physicochemical parameters and microbiological parameters like faecal coliforms, adenovirus, rotavirus, hepatitis A virus, norovirus and enterovirus were evaluated over a projected period of one year. Physicochemical parameters were measured on site using multiparameters, faecal coliforms enumerated using culture-based methods and viruses are detected using both conventional and real-time PCR. Physicochemical parameters like electrical conductivity, turbidity, free chlorine and phosphates were incompliant with the standards set by the Department of Water affairs for effluents to be discharged. Faecal coliform counts were nil for one plant (WWTP-R) where they correlated inversely (P < 0.01) with the high free chlorine. For WWTP-K, faecal coliforms were detected in 27% of samples in the range of 9.9 × 101 to 6.4× 104 CFU/100ml. From the five viruses assessed, three viruses were detected with Rotavirus being the most abundant (0-2034176 genome copies/L) followed by Adenovirus (0–275 genome copies/L) then Hepatitis A virus (0–71 genome copies/L) in the WWTP-K while none of the viruses was detected in WWTP-R. Species B, species C and Adv41 serotypes were detected from the May 2013 and June 2013 samples where almost all parameters were incompliant in the plant. The detection of these viruses in supposedly treated effluents is suggestive of these being the sources of contamination to surface water and therefore renders surface waters unsafe for direct use and to aquatic life. Although real-time PCR is more sensitive and reliable in detection of viruses, use of cell-culture techniques in this study would have been more efficient in confirming the infectivity of the viruses detected, hence the recommendation of these techniques in future projects of this nature.

Increasing nitrate concentration in ground water from improper disposal of sewage and excessive use of fertilizers is deleterious to human health as ingestion of nitrate contaminated water can cause methaemoglobinemia in infants and possibly cancer in adults. The permissible limit for nitrate in potable water is 45 mg/L. Unacceptable levels of nitrate in groundwater is an important environmental issue as nearly 80 % of Indian rural population depends on groundwater as source of drinking water. Though numerous technologies such as reverse osmosis, ion exchange, electro-dialysis, permeable reactive barriers using zero-valent iron exists, nitrate removal from water using affordable, sustainable technology, continues to be a challenging issue as nitrate ion is not amenable to precipitation or removable by mineral adsorbents. Tapping the denitrification potential of soil denitrifiers which are inherently available in the soil matrix is a possible sustainable approach to remove nitrate from contaminated drinking water. Insitu denitrification is a useful process to remove NO3–N from water and wastewater. In biological denitrification, nitrate ions function as terminal electron acceptor instead of oxygen; the carbon source serve as electron donor and the energy generated in the redox process is utilized for microbial cell growth and maintenance. In this process, microorganisms first reduce nitrate to nitrite and then produce nitric oxide, nitrous oxide, and nitrogen gas. The pathway for nitrate reduction can be written as: NO3-→ NO2-→ NO → N2O → N2. (i) Insitu denitrification process occurring in soil environments that utilizes indigenous soil microbes is the chosen technique for nitrate removal from drinking water in this thesis. As presence of clay in soil promotes bacterial activity, bentonite clay was mixed with natural sand and this mix, referred as bentonite enhanced sand (BES) acted as the habitat for the denitrifying bacteria. Nitrate reduction experiments were carried out in batch studies using laboratory prepared nitrate contaminated water spiked with ethanol; the batch studies examined the mechanisms, kinetics and parameters influencing the heterotrophic denitrification process. Optimum conditions for effective nitrate removal by sand and bentonite enhanced sand (BES) were evaluated. Heterotrophic denitrification reactors were constructed with sand and BES as porous media and the efficiency of these reactors in removing nitrate from contaminated water was studied. Batch experiments were performed at 40°C with sand and bentonite enhanced sand specimens that were wetted with nutrient solution containing 22.6 mg of nitrate-nitrogen and ethanol to give C/N ratio of 3. The moist sand and BES specimens were incubated for periods ranging from 0 to 48 h. During nitrate reduction, nitrite ions were formed as intermediate by-product and were converted to gaseous nitrogen. There was little formation of ammonium ions in the soil–water extract during reduction of nitrate ions. Hence it was inferred that nitrate reduction occurred by denitrification than through dissimilatory nitrate reduction to ammonium (DNRA). The reduction in nitrate concentration with time was fitted into rate equations and was observed to follow first order kinetics with a rate constant of 0.118 h-1 at 40°C. Results of batch studies also showed that the first order rate constant for nitrate reduction decreased to 5.3x10-2 h-1 for sand and 4.3 x10-2 h-1 for bentonite-enhanced sand (BES) at 25°C. Changes in pH, redox potential and dissolved oxygen in the soil-solution extract served as indicators of nitrate reduction process. The nitrate reduction process was associated with increasing pH and decreasing redox potential. The oxygen depletion process followed first order kinetics with a rate constant of 0.26 h-1. From the first order rate equation of oxygen depletion process, the nitrate reduction lag time was computed to be 12.8 h for bentonite enhanced sand specimens. Ethanol added as an electron donor formed acetate ions as an intermediate by-product that converted to bicarbonate ions; one mole of nitrate reduction generated 1.93 moles of bicarbonate ions that increased the pH of the soil-solution extract. The alkaline pH of BES specimen (8.78) rendered it an ideal substrate for soil denitrification process. In addition, the ability of bentonite to stimulate respiration by maintaining adequate levels of pH for sustained bacterial growth and protected bacteria in its microsites against the effect of hypertonic osmotic pressures, promoting the rate of denitrification. Buffering capacity of bentonite was mainly due to high cation exchange capacity of the clay. The presence of small pores in BES specimens increased the water retention capacity that aided in quick onset of anaerobiosis within the soil microsites. The biochemical process of nitrate reduction was affected by physical parameters such as bentonite content, water content, and temperature and chemical parameters such as C/N ratio, initial nitrate concentration and presence of indigenous micro-organisms in contaminated water. The rate of nitrate reduction process progressively increased with bentonite content but the presence of bentonite retarded the conversion of nitrite ions to nitrogen gas, hence there was significant accumulation of nitrite ions with increase in bentonite content. The dependence of nitrate reduction process on water content was controlled by the degree of saturation of the soil specimens. The rate of nitrate reduction process increased with water content until the specimens were saturated. The threshold water content for nitrate reduction process for sand and bentonite enhanced sand specimens was observed to be 50 %. The rate of nitrate reduction linearly increased with C/N ratio till steady state was attained. The optimum C/N ratio was 3 for sand and bentonite enhanced sand specimens. The activation energy (Ea) for this biochemical reaction was 35.72 and 47.12 kJmol-1 for sand and BES specimen respectively. The temperature coefficient (Q10) is a measure of the rate of change of a biological or chemical system as a consequence of increasing the temperature by 10°C. The temperature coefficient of sand and BES specimen was 2.0 and 2.05 respectively in the 15–25°C range; the temperature coefficients of sand and BES specimens were 1.62 and 1.77 respectively in the 25–40°C range. The rate of nitrate reduction linearly decreased with increase in initial nitrate concentration. The biochemical process of nitrate reduction was unaffected by presence of co-ions and nutrients such as phosphorus but was influenced by presence of pathogenic bacteria. Since nitrate leaching from agricultural lands is the main source of nitrate contamination in ground water, batch experiments were performed to examine the role of vadose (unsaturated soil) zone in the nitrate mitigation by employing sand and BES specimens with varying degree of soil saturation and C/N ratio as controlling parameters. Batch studies with sand and BES specimens showed that the incubation period required to reduce nitrate concentrations below 45 mg/L (t45) strongly depends on degree of saturation when there is inadequate carbon source available to support denitrifying bacteria; once optimum C/N ratio is provided, the rate of denitrification becomes independent of degree of soil saturation. The theoretical lag time (lag time refers to the period that is required for denitrification to commence) for nitrate reduction for sand specimens at Sr= 81 and 90%, C/N ratio = 3 and temperature = 40ºC corresponded to 24.4 h and 23.1 h respectively. The lag time for BES specimens at Sr = 84 and 100%, C/N ratio = 3 and temperature = 40ºC corresponded to 13.9 h and 12.8 h respectively. Though the theoretically computed nitrate reduction lag time for BES specimens was nearly half of sand specimens, it was experimentally observed that nitrate reduction proceeds immediately without any lag phase in sand and BES specimens suggesting the simultaneous occurrence of anaerobic microsites in both. Denitrification soil columns (height = 5 cm and diameter = 8.2 cm) were constructed using sand and bentonite-enhanced sand as porous reactor media. The columns were permeated with nitrate spiked solutions (100 mg/L) and the outflow was monitored for various chemical parameters. The sand denitrification column (packing density of 1.3 Mg/m3) showed low nitrate removal efficiency because of low hydraulic residence time (1.32 h) and absence of carbon source. A modified sand denitrification column constructed with higher packing density (1.52 Mg/m3) and ethanol addition to the influent nitrate solution improved the reactor performance such that near complete nitrate removal was achieved after passage of 50 pore volumes. In comparison, the BES denitrification column achieved 87.3% nitrate removal after the passage of 28.9 pore volumes, corresponding to 86 h of operation of the BES reactor. This period represents the maturation period of bentonite enhanced sand bed containing 10 % bentonite content. Though nitrate reduction is favored by sand bed containing 10 % bentonite, the low flow rate (20-25 cm3/h) impedes its use for large scale removal of nitrate from drinking water. Hence new reactor was designed using lower bentonite content of 5 % that required maturation period of 9.6 h. The 5 and 10 % bentonite-enhanced sand reactors bed required shorter maturation period than sand reactor as presence of bentonite contributes to increase in hydraulic retention time of nitrate within the reactor. On continued operation of the BES reactors, reduction in flow rate from blocking of pores by microbial growth on soil particles and accumulation of gas molecules was observed that was resolved by backwashing the reactors.

The access to water in the regions around Lake Victoria varies with the rainy seasons. Today the daily labor of fetching water is a heavy burden for people in the rural areas. In the process of this study farmers in the Western and Nyanza provinces in Kenya are interviewed, water samples are analysed and present rainwater harvesting techniques and purification methods are observed. As a result, suitable solutions to the problems found are discussed. An optimal system is chosen for the region with a concept selection matrix. An elaborated dimensioning tool for roof and purpose-built harvesting systems is developed. Finally a summarized manual is attached in order to raise interest for rainwater harvesting among the farmers that the non-governmental organisation SCC-Vi Agroforestry cooperates with. / Tillgången till vatten i områdena kring Victoriasjön varierar med regnperioderna. Det dagliga arbetet med att hämta vatten är idag en stor börda för människor på landsbygden. Under processen av denna studie intervjuas bönder i Western och Nyanza provinserna i Kenya, vattenprover analyseras och nuvarande regnvatteninsamlingstekniker och reningsmetoder observeras. Som ett resultat diskuteras passande lösningar på de problem som hittats. Ett optimalt val av komplett system för regionerna tas fram med hjälp av en konceptvalsmatris. Ett genomarbetat verktyg för dimensionering av tak- och ändamålsbyggda insamlingssystem utvecklas. Slutligen inkluderas en sammanfattande manual för att väcka intresse för regnvatteninsamling bland de bönder som den ideella organisationen SCC-Vi Agroforestry samarbetar med.

Les procédés membranaires hybrides (PMH) allient la filtration membranaire basse pression à l’usage du charbon actif en poudre (CAP). Afin de diminuer les coûts opérationnels du procédé, il a été proposé de laisser vieillir le CAP dans le PMH et donc de minimiser le dosage de CAP frais. Peu d’information est disponible quant à la capacité résiduelle d’adsorption de suspensions de CAP âgées. L’importance relative de l’adsorption et de la biodégradation dans les réacteurs à CAP âgés sur le traitement des composés dissous est inconnue, ce qui empêche notamment l’optimisation du procédé. <p><p>Le principal objectif de ce projet de recherche est de décrire la performance du contacteur à CAP du PMH pour l’enlèvement de l’azote ammoniacal, du carbone organique dissous (COD), du COD biodégradable (CODB) et des micropolluants. Dans ce projet, l’emphase est placée sur l’opération du PMH avec de hauts temps de rétention de CAP. <p><p>La première phase de ce projet a consisté en une série de développements méthodologiques, base nécessaire à l’étude du CAP âgé. Des méthodes permettant la quantification de la biomasse hétérotrophe et nitrifiante colonisant le CAP âgé ont mis en évidence des densités de biomasse similaires à celle du charbon actif en grain en surface de filtre biologiques. L’irradiation aux rayons gamma a été démontrée comme une méthode adéquate pour produire des témoins abiotiques à partir de CAP de 10 et de 60 jours.<p><p>La seconde partie de cette étude s’est concentrée sur la démonstration de l’efficacité du PMH pour l’enlèvement de l’azote ammoniacal, du COD, ainsi que d’un mélange de micropolluants. Les cinétiques d’enlèvements ayant lieu au sein de des contacteurs à CAP ont été simulées en laboratoire sous diverses conditions (température, concentration en CAP, âge de CAP, matrice d’eau variable, temps de contact). Deux modèles cinétiques prédisant l’enlèvement de l’azote ammoniacal et du COD dans le PMH ont été développés sur base des simulations en laboratoire suivies sur CAP neuf, colonisé et abiotique. <p><p>De manière générale, les travaux réalisés au cours de ce doctorat ont mis en évidence le rôle majeur de l’adsorption résiduelle sur l’enlèvement de la contamination dissoute. Alors que l’enlèvement d’azote ammoniacal a majoritairement eu lieu par nitrification, le COD et les micropollutants sont principalement adsorbés sur le CAP colonisé. Il a aussi été montré que la capacité d’adsorption résiduelle des suspensions de CAP âgées peut agir en tampon, permettant de faire face à une augmentation soudaine de la concentration en azote ammoniacal, en COD ou en micropolluants. Le suivi des cinétiques d’enlèvement a permis de démontrer que la concentration, l’âge de CAP et le temps de rétention hydraulique (TRH) sont trois paramètres clefs pour l’optimisation du procédé. D’un point de vue économique, un TRH inférieur à 15 min est néanmoins désiré pour limiter les coûts du procédé. Par ailleurs, l’intérêt économique associé à l’augmentation de l’âge du CAP peut-être atténué par le besoin d’augmenter la concentration en CAP si l’adsorption est le mécanisme visé. De façon générale, ce projet démontre qu’une optimisation à l’échelle pilote du procédé est nécessaire car les objectifs de traitement, la qualité de l’eau à traiter et le fait que les 3 paramètres d’opération soient inter-reliés complexifient l’optimisation du PMH. Étant donné l’impact du TRH sur le coût du PMH, de futures recherches devraient viser à l’optimisation du mélange. <p>Hybrid membrane processes (HMPs) couple membrane filtration with powdered activated carbon (PAC). In HMPs, low-pressure membranes ensure an efficient particle removal, including protozoan parasites such as Cryptosporidium, while the PAC contactor is devoted to the removal of dissolved compounds. Such processes are emerging as a promising alternative to conventional treatment chains, which no longer allow the drinking water facilities to comply with increasingly stringent regulations on the treated water quality. To decrease the operating costs associated with virgin PAC consumption, it was suggested to let the PAC age in the PAC contactor of the process. Until now, the potential of using aged PAC in HMPs has been demonstrated for ammonia and DOC removal, but the potential to remove micropollutants remains unknown. It is suggested that the biological activity in aged PAC contactors contributes significantly to the removal of the dissolved compounds. Yet, neither the extent of the biomass on the aged PAC, nor the residual adsorption capacity, was quantified. No study focused on discriminating the mechanisms responsible for the treatment when using aged PAC suspensions. Most of the data published on HMPs using aged PAC were gathered at pilot scale under warm water conditions, yet the efficiency of the process is most likely sensitive to temperature changes. There is currently little information available on the efficiency of HMPs under cold water conditions. This lack of information hinders the optimization of the HMP, leading to sub-optimal usage of aged PAC.<p><p>The main objective of this research project is to describe the performance of the PAC contactor of HMPs in removing ammonia, dissolved organic carbon (DOC), biodegradable DOC (BDOC) and micropollutants. In particular, emphasis was placed on the operation of the HMP under high PAC residence times. On a more detailed level, the objectives of this project were (1) to develop and compare methods to quantify the biomass developed on aged PAC, (2) to develop a method to produce an abiotic control for aged PAC, (3) to characterize the removal kinetics of ammonia, DOC, BDOC and micropollutants occurring in the carbon contactor of an HMP, (4) to evaluate the impact of water temperature on the performance of the carbon contactor of an HMP, (5) to discriminate the relative importance of adsorption versus biological oxidation as mechanisms responsible for ammonia, DOC and micropollutants removal in the PAC contactor of an HMP, and finally (6) to differentiate the relative importance of the hydraulic retention time (HRT), the PAC age and the PAC concentration as key operating parameters on the optimization of the performance of the PAC contactor of an HMP.<p><p><p>To set the basis on the study of aged PACs, the first part of this research project consisted in methodological developments i) to quantify the heterotrophic and nitrifying biomass colonizing aged PAC, and ii) to create a reliable abiotic control of the colonized PAC, which is required for discriminating the mechanisms occurring on aged PAC. Heterotrophic and nitrifying biomass quantifying methods developed for colonized granular activated carbon (GAC) were successfully adapted to the aged PAC. The preferred methods were the potential 14C-glucose respiration (PGR) rate and the potential nitrifying activity (PNA), as they quantify the active heterotrophic and nitrifying biomass, which is most likely responsible for the depletion of BDOC and ammonia. An alternative method to the PGR, the potential acetate uptake (PAU) rate, was developed to alleviate the logistical and budgetary issues associated with the utilization of radio-labeled glucose. The densities (per gram of dry PAC) of both active heterotrophic and nitrifying biomasses were found comparable to that of the GAC sampled from the surface of a biological GAC filter. The gamma-irradiation was demonstrated as a reliable method to produce abiotic samples from soils, and was therefore chosen to produce abiotic colonized PAC samples in this project. In order to determine the optimized dosage of gamma-rays, increased doses were applied on PAC samples. Heterotrophic plate counts and methylene blue adsorption kinetics were used to determine respectively the lowest gamma ray dose required to inhibit the bacterial activity, and the highest dose that could be applied without affecting the aged PAC adsorption capacity and kinetics. Refractory DOC (RDOC) adsorption kinetics confirmed the accuracy of the dose chosen as the adsorptive behavior of the aged PAC was not affected. PGR rates were decreased 83% at the optimized dose. The gamma-irradiation method was therefore proven efficient and used in the following work phases of this research.<p><p>The second part of this study focused on the removal of ammonia, DOC and a mixture of micropollutants. Firstly, the PAC contactor of an HMP was simulated at lab-scale to monitor ammonia removal kinetics. Three PAC concentrations (approximately 1-5-10 g/L) of three PAC ages (0-10-60 days) were tested at two temperatures (7-22°C), in settled water with ambient influent condition (100 µg N–NH4/L) as well as under a simulated peak pollution scenario (1000 µg N–NH4/L). The kinetics evidenced that ammonia flux at pilot scale limited biomass growth (HRT = 67 min). In contrast, PAC colonization was not limited by the available surface and thus, PAC concentration was not a key operating parameter under the colonizing conditions tested (5-10 g/L). Ammonia adsorption was significant onto virgin PAC but the ammonia nitrification was crucial to reach complete ammonia removal at 22°C. When using colonized PAC, the 60-d PAC offered a better resilience to temperature decreases (78% at 7°C) as well as lower operating costs than the 10-d PAC (<10% at 7°C). Significant ammonia adsorption was also evidenced on 60-d PAC suspension, most probably due to PAC and the presence of suspended solids, but not on 10-d PAC. Adsorption and nitrifying activity were superior on 60-d PAC than on 10-d PAC at 7°C. In case of peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed 50% ammonia removal on 10-d and 60-d PAC at 22°C. A kinetics based model was developed to predict ammonia removals and to determine the relative importance of the adsorption and nitrification on colonized PAC under the conditions tested. <p><p>DOC, BDOC and RDOC removals occurring in the PAC contactor of an HMP were also simulated at lab-scale. Similar conditions to that of the ammonia removal kinetics were tested. The initial ammonia concentration remained untouched in the water matrices (settled water and raw water) but the BDOC-to-DOC ratio was altered by pre-ozonation (0 to 1.5 g O3/g C). The 10-d and 60-d abiotic controls were used to discriminate DOC adsorption from biodegradation. DOC biodegradation contributed marginally to DOC removal in the investigated conditions and DOC adsorption was increased at higher temperature. An original model integrating the PAC age distribution was developed to predict DOC removal in aged PAC contactors operated at steady-state. At a mean PAC residence time of 60-d, the younger PAC fraction (25-d and less) was primarily responsible for DOC adsorption (> 80%). This fraction represents 34% of the mass of PAC in the contactor. When using a water matrix with a higher initial DOC concentration (raw water) or a lower affinity for PAC (pre-ozonated settled water), the residual adsorption capacity of that older fraction was proven useful. <p><p>Lastly, a mixture of micropollutants (atrazine, deethylatrazine (DEA), linuron, microcystin, caffeine, carbamazepine, sulfamethoxazole, diclofenac, progesterone and medroxyprogesterone) was spiked at environmentally relevant concentrations (from 130 ng/L to 33 µg/L) in settled water (0 and 0.85 gO3/gC). The micropollutants concentration depletion was monitored over a period of 7h to 48 h on 1 g/L of 0-d, 10-d, 60-d PAC and gamma-irradiated 60-d PAC. Even in presence of NOM, the spiked micropollutants were rapidly adsorbed on aged PAC. No biodegradation was observed. Removals superior to 95% were reached within 5 minutes, and direct competition with NOM did not impact the efficiency of the process when micropollutants were spiked at environmentally relevant concentrations. Therefore, HMPs operated to remove DOC and ammonia can control transient micropollutant pollution and comply with the World health Organization recommendations for atrazine (2 µg/L) and microcystin (1 µg/L). However, the stricter European regulations for atrazine and DEA (0.1 µg/L) could not be met with 10-d and 60-d PAC under the operating conditions tested. Reaching such strict treatment objective would require a specific optimization of the process. <p><p>In general, this PhD research evidenced the role of the residual adsorption of aged PAC suspensions for the treatment of dissolved compounds. From the results obtained in this project, the potential of HMPs using aged PAC to remove micropollutants was evidenced. Additional research is however required to validate this potential under varied operating conditions. The modeling work improved the understanding of aged PACs. Finally, this research work provides original information on the optimization of HMPs. The optimization of the operating parameters will vary with the water quality targeted and the quality of the influent water. The PAC concentration, PAC age and HRT are inter-related. Therefore, it is recommended to optimize the operation of HMPs at pilot scale. Seasonal variations should be accounted for. An HRT of at least 15 min is required when the biological activity is mandatory to reach the water quality objectives. Lower HRT might be applied if adsorption is favored. Finally, as the HRT has a strong impact on the total cost of the process (capital and operational expenditure), PAC contactors’ hydraulic should be the point of focus of future research.& / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

L'objectif de cette étude est de mieux comprendre comment la biodiversité influence le service de purification de la qualité de l'eau en tant que service de régulation capable de limiter la charge en polluants de l'eau naturelle. Peu d'études ont regardé comment les invertébrés (macro- et méio-faune) sont capables d'influencer le fonctionnement de la zone hyporhéique considérée, comme un réacteur biogéochimique contribuant largement au recyclage des nutriments. L'élimination du nitrate et la dénitrification sont utilisés comme indicateur de ce service dans les rivières afin de pouvoir suivre son évolution spatiale et temporelle. Dans cette thèse, la relation fonctionnelle entre le taux de réduction des nitrates et les organismes participant à l'expression de ce service est testée à différentes échelles d'étude allant du microcosme jusqu'à l'habitat hyporhéique d'un méandre de large rivière, la Garonne. Cette relation est mise en évidence dans une série de colonnes d'infiltration reproduisant le lit de rivière avec sa communauté benthique (projet Inbioprocess). Dans cette expérience, un gradient de biodiversité a été créé avec des combinaisons de communautés +/- biofilm, +/- méiofaune et +/- macrofaune pour tester leur influence sur l'élimination du nitrate avec et sans pesticides dans le cadre du projet Inbioprocess. Les résultats suggèrent l'influence des interactions entre communautés, sur le taux de réduction des nitrates qui est supérieur quand les invertébrés sont présents (11.8 ± 1.2) par comparaison avec les conditions sans invertébrés (7.7 ± 1.4 mg N l-1d-1 ; moyenne ± erreur standard (m ± ET)). Ces interactions ont également été suggérées comme favorisant le retour de la capacité de réduction des nitrates en présence de pesticides, utilisé comme source de stress, dans l'eau des microcosmes. Ces résultats de laboratoire montrent l'influence des interactions trophiques et non trophiques entre les différents niveaux trophiques de ce réseau, avec probablement l'implication des espèces les plus résistantes pour expliquer la capacité potentielle de résilience du système. L'existence de cette relation fonctionnelle de type "top-down" a ensuite été explorée en conditions in situ. Les taux de rétention mesurés dans 9 cours d'eau européens (projet STREAMES) ont été estimés à l'échelle du tronçon de rivière à 1.64 ± 2.39 (m ± ET) mg NO3--N m-2.min-1. L'influence des communautés d'invertébrés sur le taux de réduction des nitrates se révèle statistiquement comme aussi importante que celle des facteurs physicochimiques dans l'ensemble des tronçons explorés. L'étude des traits biologiques des communautés d'invertébrés a permis de préciser le type de communauté le plus corrélé aux processus d'élimination des nitrates. Ces organismes sont majoritairement interstitiels vivant dans les sédiments grossiers et avec des modes d'alimentation de type brouteurs de biofilm. Dans la zone hyporhéique de la zone humide alluviale de Monbéqui (projet Attenagua), la corrélation positive de la communauté d'invertébrés avec le taux de dénitrification a été seulement visible pendant automne. Cette période est considérée comme un moment propice pour l'observation de la relation diversité-fonction dans ce milieu. / This PhD study aims to understand how the biodiversity influences the water purification processes in the hyporheic zone of running water, as an important regulating service that reduces the quantity of pollutants in freshwater ecosystems. Few studies have focused on how the invertebrate community influences the functioning of hyporheic zones, which are considered as a biogeochemical reactor that largely contributes to nutrient cycling capacity of the rivers. Nitrate retention or denitrification functions in hyporheic zones are used as indicators for the water purification service. The relationship between the nitrate removal function and its associated biodiversity was tested at different scales from indoor microcosms to in-stream reaches and the hyporheic habitat of a large river (Garonne) meander, under natural and stressful conditions. First, the linkage between invertebrates and the nitrate (NO3-) removal function was given in evidence in a series of infiltration columns that mimicked the riverbed conditions with its benthic communities. A gradient of community diversity was created with biofilm, meiofauna and macrofauna communities' combination in different treatments. It enabled to test the influence of the invertebrate community on the NO3- removal rates with and without pesticides during the Inbioprocess project. The results implied the influence of invertebrate and microbial cross-community interactions on NO3- removal rates, which was higher with invertebrate communities in the sediments (11.8 ± 1.2) than without (7.7 ± 1.4 mg N.l-1.d-1). These findings suggested a top-down control of invertebrates on the microbial activities. These interactions were also depicted at the source of the recovery of the NO3- removal capacity when facing stressful conditions due to addition of pesticide in the experimental water. These laboratory findings highlighted the importance of multi-trophic level interactions in the hyporheic habitat, with probable implication of the more resistant species in the resilience capacity of this system. The occurrence of the top-down linkage was then explored in in situ habitats. The NO3- removal rates measured at the reach scale in 9 European streams during the STREAMES project ranged from 0.04 to 10.75 with an average of 1.64 ± 2.39 mg NO3--N m-2.min-1 (Mean ± SE). The results suggested that not only physico-chemical and hydrological factors, but also macro-invertebrate assemblages may influence nitrate removal. Some functional groups positively correlated with nitrate reduction were biofilm grazers and interstitial organisms associated with macro-porous substrate. In the hyporheic water of Monbequi meander of the Garonne river, the positive correlation between invertebrate diversity and the potential denitrification rates was only visible during the autumn season, suggesting a potential "hot moment" for the observation of this correlation between biodiversity and ecosystem function in fields.

Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.

Wastewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community. Prevalence of Listeria in terms of total counts was 100 percent across all sampled locations. Free-living Listeria species showed prevalence ranging from 84-96 percent across the sampling locations; while Listeria species attached to large (180 μm) planktons exhibited prevalence ranging from 75 percent to 90 percent. The prevalence of medium-sized (60 μm) plankton associated Listeria species varied between 58 percent and 92.5 percent; whereas those of Listeria species attached to small (20 μm) planktons ranged from 65-100 percent across all three communities. Listeria prevalence was generally a reflection of the turbidity of the water system, with free-living Listeria species being more prevalent than plankton associated cells in the relatively less turbid rural and urban waters compared to the more turbid peri-urban waters where plankton attached cells were more prevalent in comparison with their free living counterparts The final treated effluent quality fell short of recommended standards for turbidity, chemical oxygen demand and phosphate across all three communities. In addition, the final effluent of the rural treatment plant also fell short of recommended standard for NO3, while that of the urban treatment plant did not comply with acceptable limits for dissolved oxygen and nitrite. Other physicochemical parameters were compliant with set standards after treatment. An inverse relationship was observed between chlorine residual and listerial density across the sampled facilities; the effect of chlorine was however not enough to eliminate the pathogen from the water systems. At the urban treatment plant and its receiving watershed, pH, temperature, EC, turbidity, TDS, DO, and nitrate varied significantly with season and sampling point (P < 0.05; P < 0.01). Salinity also varied significantly with sampling point (P < 0.01), while COD and nitrite varied significantly with season (P < 0.05). Although, the treated effluent fell within recommended water quality standard for pH, TDS, nitrate and nitrite, it fell short of stipulated standards for other parameters. Whereas the microbial quality of the secondary treated effluent at this (urban) facility fell short of recommended standard after secondary treatment, its physicochemical quality were generally compliant with recommended standards for reuse wastewater in agriculture and aquaculture. Listeria pathogens isolated from effluents of the rural wastewater facility were sensitive to 11 (55 percent) of the 20 test antibiotics, and showed varying (7-71 percent) levels of resistance to 8 antibiotics; whereas those isolated from the peri-urban community showed sensitivity to 6 (30 percent) of the 20 test antibiotics, and varying (6-94 percent) levels of resistance to 12 antibiotics; while the urban effluent isolates were sensitive to 3 (15 percent) of the 20 test antibiotics, and showed varying (4.5-91 percent) levels of resistance to 17 antibiotics. Multiple antibiotic resistances involving 78.5-100 percent of isolates and antibiotics combination ranging from 2-10 antibiotics was observed across the sampled locations. Penicillin G and ampicillin showed remarkably high (64-91 percent) phenotypic resistance across the three sampled facilities. Other antibiotics, to which isolates showed significant resistance, were linezolid (22-88 percent); erythromycin (43-94 percent) and sulphamethoxazole (7-94 percent). Two of the 14 Listeria strains isolated from the rural effluents were positive for ereA and sul1 antibiotic resistance genes; while sulII genes were detected in five of the 23 Listeria isolates from the urban effluent and none was detected in isolates from the peri-urban community. The presence of antimicrobial resistance genes in the isolates did not correlate with phenotypic antibiotic resistance. The current study demonstrated that Listeria pathogens easily survived the activated sludge treatment process as free-living and plankton attached entities and suggests that municipal wastewater treatment plants are a significant source of multiple resistant Listeria pathogens in the South African aquatic milieu. While the physicochemical quality of the urban final effluent suggests that it is a major source of pollution to the receiving watershed, the secondary effluent quality demonstrated a great potential for use in agriculture and aquaculture.

The present thesis is focused on the synthesis and environmental applications of polyaniline and its nanocomposites. It is organized in six chapters and brief discussions of the contents of the individual chapters are given below. Chapter 1 reviews two important water purification methods: adsorption and photocatalysis, which are widely discussed in literature. A general introduction to conducting polymers has been given and their photocatalytic activity has been described. Chapter 2 reports the application of polyaniline emeraldine salt for the removal of anionic dyes from aqueous solutions by adsorption. A possible mechanism for the anionic dye adsorption by PANI emeraldine salt has been proposed. The electrostatic interaction between the positively charged PANI backbone and dye anions is responsible for significant dye adsorption. The kinetic parameters for the adsorption of anionic dyes on PANI have also been determined. In Chapter 3, we investigate the adsorption and desorption of anionic dyes from aqueous solution by PANI doped with different protonic acids. PANI with three dopants, namely p-toluene sulfonic acid (PTSA), camphor sulfonic acid (CSA) and dodecyl benzene sulfonic acid (DBSA) were used to adsorb various dyes. The adsorbed dyes were desorbed from the polymer by using a basic aqueous solution. It was found that the adsorption of dye is dependent on the size and nature of the dopant acids. The influence of different dopants on the adsorption and desorption kinetic parameters was also examined. In chapter 4, the inherent property of PANI to adsorb dyes has been explored for the detection of dyes by electrochemical method. The changes in the CV of PANI film coated on Pt electrodes on addition of dye have been employed for detection of dye in aqueous solution. Furthermore, PANI coated stainless steel (SS) electrodes show a change in current intensity of Fe2+/Fe3+ redox peaks due to addition of dye in the electrolyte solution. Chapter 5 describes the synthesis and characterization of polyaniline-grafted-chitosan (CPANI) with different grafting ratios. The mechanical properties and the crystallinity of CPANI were investigated by means of nanoindentation and X-ray diffraction experiments, respectively. CPANI has been further self-assembled into multilayer thin film via versatile and simple layer-by-layer (LbL) approach. Negatively charged hyaluronic acid (HUA) was used as complementary polyelectrolyte for the self-assembly. LbL growth of the multilayer thin films has been monitored with UV-vis spectral analysis as well as by AFM. The formation of thin film has been further characterized by SEM. The pH responsive behavior of CPANI/HUA multilayer thin film has been investigated. Reusability of this thin film has been investigated by repeating the pH responsive experiments for 10 cycles. Chapter 6 is focused on the preparation of nanocomposite thin films of CPANI/PSS/TiO2 via LbL approach. LbL growth of this self-assembly was monitored by UV-vis spectral analysis and porous nature was observed from SEM images. Poly (styrene sulfonate) (PSS) was used as bridging layer between TiO2 nanoparticles and CPANI for the multilayer self-assembly. Incorporation of CPANI within this LbL self-assembly enhanced the dye degradation ability of the thin film by increasing the availability of dye molecules around the TiO2 nanoparticles. Furthermore, CPANI may act as a sensitizer to enhance the photocatalytic activity of TiO2. The effects of surface area of the multilayer thin film and amount of catalysts (TiO2 nanoparticles) incorporated in the self-assembly were described based on the kinetics of the dye degradation reactions. The same multilayer thin film can be efficiently used for dye degradation several times. The work presented in this thesis utilizes unique dye adsorption properties of PANI and its copolymers. The change in conductivity of PANI after dye adsorption and the electrochemical dye detection in aqueous medium promise the potential of PANI as a dye sensing material in waste water at very low concentration. The nanocomposites of CPANI/PSS/TiO2 present a novel material for photocatalysis.

Made available in DSpace on 2017-06-01T18:20:40Z (GMT). No. of bitstreams: 1 edson_rodrigues_vieira.pdf: 14210743 bytes, checksum: c69ef6f544af01646043361a15e15d51 (MD5) Previous issue date: 2013-05-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The microbial physiology is a promising area of biotechnology for the synthesis of compounds of high value. The micro-organisms have advantages because of their shorter generation facilities to physiological and genetic changes and the wide variety of metabolic processes. The aim of this study was to degrade oils and fats from lipases produced by Yarrovia lipolytica. Factorial designs were used to investigate the effects of variables in three stages: fermentation for lipase production, bioproduct formulation for stabilization the catalytic action of lipases and treatment of whey for degradation of fats and oils. In the presence of a vegetable oil residue at 3 % and ammonium chloride at 0,2 g.L-1, during 48 h at 28 oC, lipases were produced under submerged cultivation. The cell-free liquid metabolic was stability with sodium sorbate at 0.5 %, glycerol at 5 %, RENEX-95 at 10 %. This bioproduct presented 177 UI.mL-1 of the lipase activity during 30 days of storage at room temperature (27 - 30 °C); it showed optimum pH at 5.0 and 7.0, optimum temperature of 50 oC and thermal stability for 120 min with retention of 100 % of the enzyme activity at 50 oC and pH 5,0. The application of the bioproduct at 7 % during 12 h degraded 98 % of oils and fats present in cheese whey. The lipases produced by Y. lipolytica and formulated with stability agents have potential to be applied in the degradation of oils and fats. / A fisiologia microbiana é uma área promissora da biotecnologia para a síntese de compostos de elevado valor agregado. Os micro-organismos apresentam vantagens devido ao menor período de geração, às facilidades de modificações fisiológicas e genéticas e à grande diversidade de processos metabólicos. O objetivo deste trabalho foi degradar óleos e gorduras de efluente lácteo por lipases produzidas por Yarrovia lipolytica. Planejamentos fatoriais foram utilizados para investigar os efeitos de variáveis em três etapas: em fermentação para produção de lipases, em formulação de bioproduto com atividade lipásica para estabilização da ação catalítica da enzima e em tratamento de soro de queijo para degradação de óleos e gorduras. Na presença de resíduo de refinaria de óleo vegetal a 3 % e cloreto de amônio a 0,2 g.L-1 com 48 h a 28 oC, lipases foram produzidas sob cultivo submerso. O líquido metabólico livre de células com atividade lipásica foi estabilizado com sorbato de sódio a 0,5 %, glicerol a 5 % e RENEX-95 a 10 %. Esse bioproduto apresentou 177 UI.mL-1 da atividade enzimática durante 30 dias sob armazenamento à temperatura ambiente (27 - 30 oC); pH ótimo 5,0 e 7,0, temperatura ótima de 50 oC e estabilidade térmica durante 120 min com retenção de 100 % da atividade enzimática a 50 oC e pH 5,0. A aplicação de 7 % do bioproduto durante 12 h de tratamento de efluente lácteo degradou 98 % dos óleos e gorduras presentes no soro de queijo. As lipases produzidas por Y. lipolytica e formuladas com substâncias estabilizadoras tem potencial para serem aplicadas na degradação de óleos e gorduras.

Det här projektet har varit på uppdrag av Kalmar Energi AB och har utförts på kraftvärmeanläggningen Moskogen. Projektet syftade till att undersöka om återvinning av rökgaskondensat till spädvatten var möjlig och ekonomiskt försvarbart. Denna åtgärd skulle potentiellt kunna minska anläggningens råvattenkonsumtion och det skulle leda till en ekonomisk besparing. Åtgärden skulle även bidra till att anläggningen blev mer självförsörjande och mindre känslig vid störningar på det lokala råvattennätet. Mätningar av flöden på rökgaskondensatsproduktionen, halter av föroreningar och råvattenkonsumtionen gav viktiga parametrar för kontakt med leverantör av reningssystem. Samarbete upprättades med Eurowater AB där två olika reningsanläggningar togs fram och delgavs Kalmar Energi AB. Kostnaden för de två olika förslagen och respektive råvattenbesparing gav två avskrivningstider för investeringarna. Slutsatsen som drogs av projektet var att en installation av en reningsanläggning för återvinning av rökgaskondensatet var möjlig. / This project has been commissioned by Kalmar Energi AB and has been carried out at the CHP plant Moskogen. The project aimed to investigate whether recycling of flue gas condensate was possible and economically justifiable. This measure could potentially reduce the plant´s raw water consumption and would result in economic savings. The measure would also help the plant become more self-sufficient and less sensitive to disturbances on the local raw water distribution net.  Measurements of the flow of flue gas condensate, levels of pollution and raw water consumption gave important parameters for contact with the purification supplier. We entered a collaboration with Eurowater AB where two different purification plants were presented to Kalmar Energi AB. The cost of the two different proposals and their respective raw water savings gave two different payback periods in which the initial investment would be recouped by the client. The conclusion drawn from the project is that the installation of a purification plant for recycling of flue gas condensate was possible.